Fuse elements are commonly used in integrated circuits to improve manufacturing yield or customize a circuit. Large numbers of fuses are presently used to implement increasingly sophisticated integrated circuit programming. The implementation of a particular design can require the blowing of thousands of fuses of an integrated circuit. To obtain high numbers of properly programmed devices, the fuses must be blown with an extremely high yield. Continuing refinements in the materials and processes used to fabricate integrated circuits with increasingly smaller and faster transistor components present constant new challenges to fuse designs.
In addition, a large process variation during fabrication operations usually results in either under-programming or over-programming from die to die and from wafer to wafer. Under-programming may be caused by a high resistance of the pre-burn fuse element and/or weak transistor. Over-programming may be caused by a low resistance of the pre-burn fuse element and/or strong transistor. Both of these results are undesirable. Under-programming leads to an incorrect result because a fuse is not completely blown. Over-programming may cause collateral damage, as well as recovery of open fuses, leading to low manufacturing yield and reduced reliability.
It is within this context that the embodiments arise.